The present invention relates to the general field of electrical power supply circuits. The invention relates more precisely to a power supply circuit for electronic equipment that might be affected by overheating or by a fire, e.g. an electronic card of an aeroengine computer.
Document FR 2 957 667 describes a device and a method for detecting overheating affecting an aeroengine computer. When overheating is detected, the computer generates a cutoff signal having the effect of ordering closure of a fuel cutoff valve. The engine is then no longer fed with fuel, thereby making it possible to avoid the engine overspeeding in uncontrolled manner. Furthermore, the cutoff signal can have the effects of ordering actuators of the engine (other than the fuel cutoff valve) to be disconnected and of switching off their power supplies.
Nevertheless, the behavior of the computer in the event of overheating is not predictable, and it is therefore not possible to be certain that unwanted commands will not be issued to the cutoff valve, to the actuators, or to their power supplies, with the effect of causing the engine to restart.
Furthermore, if the pilot generates a computer reinitialization signal (e.g. by moving a fuel cutoff switch from an ON position to an OFF position) while the overheating is still present, then the cutoff signal is no longer generated and that too might have the effect of restarting the engine.
One potential solution is to make cutoffs irreversible.
For example, one possible lock would consist in storing information to the effect that overheating has been detected in a non-volatile memory of the computer. Thus, if the power supply to the actuators is restarted in untimely manner, and even if the fire has disappeared, the computer will once more issue an order to cut off the engine and the power supply to the actuators as a result of this information that has been saved in non-volatile memory.
Nevertheless, under such circumstances, after overheating has been detected and the engine has been cut off, the pilot has no way of restarting the engine, since the lock serves to make the cutoff irreversible. That can turn out to be very constraining in the event of the other engine of the aircraft also failing or in the event of overheating being detected in untimely manner.
There therefore exists a need for an aeroengine to be cut off in reliable manner in the event of overheating being detected, while nevertheless making it possible for the pilot to restart the engine, if necessary.